<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>盒子阴影</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        div {
            width: 300px;
            height: 300px;
            background-color: pink;
            box-shadow: 10px 10px 20px 10px rgba(0, 0, 0, .3);
        }
    </style>
</head>

<body>
    <div>

    </div>

</body>

</html>